Electro-fishing circuit means with safety circuit



I Oct. 2, 1956 c. o. KREUTZER I 2,764,832

ELECTRO-FISHING CIRCUIT MEANS WITH SAFETY CIRCUIT Filed Aug. '2, 1955 IN V EN T 0R. CONRADI N OTTO KREUTZER ATTORNEY United States Patent ELECTRO-FISHING CIRCUIT MEANS WITH SAFETY CIRCUIT Couradiu Otto Kreutzer, Meersburg, Germany, assignor to Fish Products Company, Lewes, Del., a corporation of Delaware Application August 2, 1955, Serial No. 525,933 6 Claims. (Cl. 43-17.1)

In salt water electro-fishing, short current impulses are discharged from one immersed electrode through the fishing water to another immersed electrode. Usually one electrode is mounted on the hull of the mother ship in position to be immersed at all times. Normally the other electrode is carried by another vessel and lowered into the water when needed. Because of the high operating voltage of this equipment, it is highly desirable to prevent the high voltage energization of the equipment before both electrodes are immersed.

The principal object of this invention is to accomplish the foregoing objective in a simple, easy and relatively foolproof manner.

Another important object is to accomplish it through the use of a low voltage auxiliary or control circuit which does not require the extension of additional wires out into the fishing waters or the use of additional electrodes but which, on the contrary, may be integrated with the heart of the electro-fishing circuit means on the mother ship.

My invention resides in the use of a normally open safety circuit which is operated to energize the regular electro-fishing electrodes with a harmless electrical impulse during spaced intervals offset to those reserved for the electro-fishing impulses. These offset signal impulses are inoperative to produce an effective signal current before both electrodes are immersed because the resistance or impedance of the circuit from one electrode to another is too high. When both electrodes are immersed, that impedance drops to a low value causing the signal current to rise to a relatively high value at and above which it is operative to condition the electro-fishing circuit means for normal operation.

The invention is illustrated in the accompanying drawing wherein:

Figure 1 schematically illustrates an electro-I'ishing circuit system of conventional character into which a control circuit embodying my invention is integrated; and,

Figure 2 illustrates the space or time relationship between electro-fishing impulses and the impulses of the control currents employed in practicing my invention.

The circuit arrangement used in the drawing to illustrate my invention may be broadly described as a two element embodiment comprising: 1) discharge circuit means connected to said electrodes and operative, when activated at spaced intervals, to energize said electrodes with correspondingly spaced electro-fishing impulses; and (2) control circuit means connected to said electrodes and operative, when closed at spaced intervals, offset to those of said discharge circuit means, to energize said electrodes with correspondingly spaced offset signal impulses to establish an intermittent signal current which is strong when the admittance between said electrodes is above a certain value and relatively weak when said admittance is below said certain value and which, when strong, is operative to activate said discharge circuit means.

2 CONVENTIONAL DISCHARGE CIRCUIT MEANS The discharge circuit means conventionally comprises: a normally-open electrically-charged discharge circuit operative, when closed at spaced intervals, to energize the electro-fishing electrodes with correspondingly spaced electrical impulses and thereby establish an impulse current flow when said electrodes are electrically connected to each other; and a normally-open conditioning circuit operative, when both closed and activated, to close said discharge circuit at said correspondingly spaced intervals.

Conventional discharge circuit This circuit includes a D. C. generator 1 working continuously to charge a condenser 2, which operates to energize the electro-fishing electrodes intermittently, at controlled spaced intervals, by discharging intermittent impulses through the main electrode circuit. Each impulse flows from the positive terminal of the condenser 22 successively through line 3, an ignitron section embracing parts 4 through 8, line 9, one electrode 10, the seawater, the other electrode 11 and line 12 back to the other terminal of condenser 2.

The ignitron section, which connects line 3 to line 9, comprises two pairs of ignitrons, designated by the numerals 4, 5 and 6, 7 respectively. The ignitrons of each pair are connected in series with each other through the same condenser 8. Thus, the serially connected ignitrons of one pair 4, 5 form one branch connection across lines 3 and 9 with the current flowing one way through ignitrons 4, 5 and condenser 8 while the serially connected ignitrons of the other pair 6, 7 form a parallel branch connection across lines 3 and 9 with the current flowing the same one way through ignitrons 4, 5 and the reverse way through condenser 8.

Each of the ignitron branches normally is open at each ignitron because these devices normally are not conductive. These branches are made to fire alternately; hence the branches are closed alternately by simultaneously rendering the ignitrons of one pair conductive, during each even interval of one sequence or series of firing intervals, and those of the other pair conductive, during each alternate or odd interval of the same sequence. To do this, each ignitron is provided with a conventional conditioning circuit means which operates to establish a flow of charging current through the ignitron to render it conductive.

Conventional conditioning circuit The conditioning circuit means for ignition 4 includes a power supply 15 connected through transformer 16 to the midpoints of both the half wave rectifier 17 and the condensers 18 which operate to charge condenser 19. This condenser 19 is electrically connected to appropriate terminals of ignitron 4 through line 20 containing switch 40 and line 21 so that, when electrically charged, it will discharge through ignitron 4 when switch 4 1% is closed. The conditioning circuit means for ail other ignitrons are identical; hence the same numerals are used to designate the same parts except that the switches, which correspond to switch 40, are, for ignitron 5, 6 and '7 designated by the numerals 50, 60 and 70 respectively.

The conditioning circuit switches 49 and 50 for the ignitrons of one branch are closed during each even interval of one sequence while the switches 6t"! and 70 for the ignitrons of the other branch are closed during each alternate or odd interval of the same sequence. This is accomplished by appropriately connecting all of these switches through a suitable linkage 25 to an eccentric cam 26 which operates to close switches 40 and 50 at the zero degree position, close'switches 60 and 70 at the Conventional operation lnoperation, the cam 26 will operate at the rotational speed required to close switches 40 and 50 simultaneously at a desired frequency which, as explained in co-pending U. S. application of Serial Number 468,098, filed Nov. 10, 1954, may be in the low rate range required to scare the fish or the medium rate range required to control the movement of the fish or the high rate range required for fish stunning or killing purposes. Whatever the rate may be, one pair of ignitrons in one branch will be rendered conductive at the even intervals and the other pair of CONTROL CIRCUIT MEANS in accordance with my invention, a control circuit means is provided to test the electrical impedance or admittance of the medium between the electro-fishing electrodes continuously at spaced intervals so as to determine and redetermine whether or not those electrodes are immersed, and to activate the discharge circuit means when the tests show, and so long as they continue to show, that the admittance is at a proper low value.

This circuit means comprises: a normally-open electrically-charged control circuit operative, when closed at spaced intervals which are oifset to the intervals prevailing in the discharge circuit means, to energize said electo-fishing electrodes and 11 with correspondingly spaced offset electrical impulses which causes a strong intermittent signal current to fiow when the impedance between electrodes is low and a weak impulse signal current to flow when that impedance is relatively high; and means responsive to a strong signal current to activate said discharge circuit means.

Control circuit The control circuit includes a switch 30 which is connected by linkage a to cam 26 at a point such that it will be closed at the 90 and 270 positions of cam 26, these positions being oifset from and at right angles to the zero degree position, at which the cam closes switches 40 and 50, and the 180 position, which closes switches 60 and '70. The control circuit operates from power supply 15 through transformer 27 and full wave rectifier 28 to charge condenser 29. This condenser is electrically connected, on one side, to electrode 10, through switch 30 and line 31, and, on the other side, to electrode 11, through lines 32 and 33.

When at least one of the electro-fishing electrodes 10 or 11 is out of the water, a path of high resistance or low admittance will extend between such electrodes. So long as this condition occurs, the control circuit will intermittently energize the electrodes 10 and 11 with a succession of spaced low voltage impulse and these impulses Will, in turn, establish between electrodes a weak impulse signal current, the impulses of which range in strength or amplitude from a certain value downwardly to little or nothing. As soon as both electrodes 10 and 11 are initially immersed in a medium of low impedance or high admittance, such as sea water, the same low voltage signal impulses will establish a succession of relatively strong current impulses 37, to which the responsive means will respond in activating the discharge circuit means.

Responsive means The responsive means operates, through relay contacts 34, which are normally open, to complete the connection of power supply 15 to the transformers 16 of the various conditioning circuits. The responsive means, therefore, includes the relay coil 35, which controls the contacts 34, this coil 35 being in series with the control circuit. The coil 35 is bridged by a condenser 36 in order to smooth out its operation.

Operation Obviously when the signal current strength of the control circuit is below a certain value, the coil 35 will be unable to close the contact 34. When the signal current rises above that value, as will be the case upon the immersion of both electrodes in salt water, the coil 35 becomes effective to close contacts 34. The closure of contacts 34 results in the supply of the power to all of the conditioning circuits and thus conditions them for operation upon the closure of the switches, respectively, 40, 50, 6t) and 70.

When switches 40 and 50 are closed current will flow through ignitrons 4 and 5 rendering them conductive. When they become conductive, the condenser 2 will discharge an electro-fishing impulse 38 through the discharge circuit. As cam 26 continues to turn it will again close switch 30 of the control circuit sending out another impulse 37. Ultimately the cam 26 reaches a position which it closes switches 60 and 70 and energizes the corresponding conditioning circuits thereby causing a flow of current through ignitrons 6 and 7. These ignitrons now become conductive which result that another electro-fishing impulse 38 is discharged. Naturally this type of operation is repeated as long as the control circuit keeps switches 34 closed. As soon as switch 34 opens the discharge circuit means will be rendered inoperative.

Before passing it may be noted first that the power supply 15 may be any commercially available supply of power such as the v. 60 cycle A. C. current normally available commercially. Second, the frequency of signal current impulses may differ from that of the electro-fishing impulses as by omitting the alternate impulses 37 which are indicated in dotted lines.

Having described my invention I claim:

1. An arrangement for preventing the energization of electro-fishing electrodes so long asthey are not immersed in salt water comprising: fishing electrodes discharge circuit means operative, when activated, to energize said electrodes with an electro-fishing impulse at regularly spaced intervals; and control circuit means operative, when closed at spaced intervals offset to those of the discharge circuit means, to energize said electrodes with correspondingly spaced signal impulses and thereby establish an intermittent signal current, which is strong when the admittance between said electrodes is above a certain value and relatively weak when said admittance is below said certain value and which, when strong, is operative to activate said discharge circuit means.

2. The arrangement of claim 1 wherein the control circuit means includes; a normally-open electrically-charged control circuit operative, when closed at said offset spaced intervals, to energize said electro-fishing electrodes with said signal impulses which cause said strong or weak signal currents to flow.

3. The arrangement of claim 2 including: means responsive to said strong signal current to activate said discharge circuit means.

4. The arrangement of claim 1 wherein: said discharge circuit means includes a normally-open electricallycharged discharge circuit operative, when closed at said spaced intervals, to energize said electro-fishing electrodes with said electro-fishing impulses, and a normally-open conditioning circuit operative, when both closed and activated, to close said discharge circuit at said spaced intervals; and said control circuit weak current is inoperative to activate said conditioning circuit.

5. The arrangement of claim 4 wherein the control circuit means includes: a normally-open electrically-charged control circuit operative, when closed at said offset spaced intervals, to energize said electro-fishing electrodes with said signal impulses which cause said strong or weak signal currents to flow.

6. The arrangement of claim 5 including: means responsive to a strong signal current to activate said circuit 10 means.

References Cited in the file of this patent UNITED STATES PATENTS Alexanderson Oct. 14, 1941 Smede July 23, 1935 Dawson Nov. 4, 1941 FOREIGN PATENTS Great Britain June 24, 1953 Germany Sept. 20, 1954 

